In recent years, in view of energy saving and environmental conservation, illumination apparatuses (such as light-emitting diode lamps) using a light-emitting diode (hereinafter also referred to as “LED”) as a light source have been increasingly used in place of incandescent lamps or fluorescent lamps. Conventional illumination apparatuses using LEDs as the light source, however, emits light only in the forward direction (the light emission direction from the light source), and cannot perform wide-range light emission unlike incandescent lamps or fluorescent lamps. Consequently, unlike incandescent lamps or fluorescent lamps, the conventional illumination apparatuses cannot illuminate a room over a wide range by utilizing the reflection light of the ceiling and walls.
To make the light distribution characteristics of the conventional illumination apparatuses using LEDs as the light source close to the light distribution characteristics of incandescent lamps or fluorescent lamps, it has been proposed to control the light distribution of light emitted from LEDs by a light flux controlling member (see, for example, PTL 1).
The light flux controlling member (light emission direction conversion device) disclosed in PTL 1 includes an incidence surface that is so disposed to face a light-emitting element and to intersect the optical axis of a light-emitting element (LED), a recessed emission surface disposed on the side opposite to incidence surface, and an inclined surface disposed on a lateral side so as to connect the incidence surface and the emission surface. In the light flux controlling member disclosed in PTL 1, the light emitted from the light-emitting element with a small emission angle with respect to the optical axis of the light-emitting element enters the light flux controlling member from the incidence surface, and then reaches a center portion of the emission surface without being reflected by other surfaces. Then, the light reaching the emission surface is emitted forward from a center portion of the emission surface. In addition, the light emitted from the light-emitting element with a large emission angle with respect to the optical axis of the light-emitting element enters the light flux controlling member from the incidence surface, and then reaches the external edge of the emission surface. The light reaching the emission surface is reflected by the light emission surface, and then emitted laterally or rearward from the inclined surface. In addition, the light having a still larger emission angle with respect to the optical axis of the light-emitting element enters the light flux controlling member from the light incidence surface, and then reaches the inclined surface without being reflected by other surfaces. The light reaching the inclined surface is reflected by the inclined surface toward the emission surface. The light reflected by the inclined surface is emitted forward from the emission surface.